We seek support to analyze existing data from the Oregon Adolescent Depression Project (OADP) to better understand the pathways into and out of major depressive disorder (MDD) and the processes that mediate and moderate risk during the peak incidence period of adolescence-young adulthood. The OADP is a multi-generational project that includes a study of the prevalence and risk factors for adolescent psychopathology in a large community sample; a longitudinal follow-up of participants into young adulthood; a family study of first-degree relatives; and a longitudinal study of their children. We seek to extend previous OADP grants by addressing four broad issues that integrate these components using state-of-the-art data analytic procedures: 1) Onset of MDD in adolescents and young adults. Having a depressed parent is a critical risk factor for MDD. We will examine the specificity of the parental MDD-offspring MDD association and factors that moderate risk for MDD in offspring of depressed parents; explore environmental and person characteristics that mediate the relation between parent and offspring MDD; and compare risk factors for first-onset of MDD in adolescence versus young adulthood. 2) Course of MDD in adolescents and young adults. Adolescent MDD has a variable course. We will explore whether parental MDD is a useful marker for divergent pathways out of MDD; determine whether risk factors for first onset versus recurrent MDD differ; identify predictors of cumulative depression over time; and explore whether adolescents and young adults are changed or "scarred" by the experience of MDD. 3) Stress and depression. MDD is associated with elevated stress both before and after episodes. Using seven annual assessments of life events and depressive symptoms between adolescence and young adulthood, and latent growth curve and growth mixture modeling, we will examine reciprocal relationships between stress and depression; whether parental MDD and personal history of MDD moderate stress-depression relationships; and individual differences in stress trajectories. 4) Behavior problems in young children of depressed parents. The multigenerational structure of the OADP provides an opportunity to examine some of these issues in the children of the original OADP cohort. We will use latent growth curve modeling to identify distinct groups of developmental trajectories of psychopathology in offspring, and examine grandparental, parental, and familial predictors of these trajectories.